The present invention relates to a tap for withdrawing fluid from a container comprising an outer tube, which can be fitted in an opening of the container in sealing engagement and in which an inner tube is received in sliding and sealing engagement, an inlet opening arranged in the outer tube and an inlet opening arranged in the inner tube which communicates with an outlet opening in the inner tube that can be transferred by a corresponding movement of the inner tube from a closed position, in which the inner tube is completely inserted in the outer tube and in which the inlet openings of the outer tube and the inner tube do not overlap, to an open position in which the inlet openings of the outer tube and the inner tube are at least partially aligned one with the other, there being provided between the outer tube and the inner tube guide means comprising an axial portion that permit the inner tube to be pulled out of the outer tube to a ready position in which the inlet openings of the outer tube and the inner tube are not yet aligned one with the other.
The present invention further relates to a container equipped with such a tap.
A tap, and a container equipped with such a tap, of the before-mentioned type are known from WO 97/16350.
The known container preferably is a party keg having a capacity of 5 liters or 10 liters from which beer is to be tapped via an integrated tap. To this end, an outer tube is received in an opening provided at the lower end of the party keg by means of a plug-like sealing element. An inner tube is guided in the outer tube to slide in axial direction. Both the outer tube and the inner tube are provided with an inlet opening, and the inlet opening of the inner tube communicates, via the inner space of the inner tube, with an outlet opening provided on the outer lower end of the outer tube. The inner tube can be pulled out from a closed position, in which the inner tube is fully inserted in the outer tube and in which the inlet openings do not overlap each other by any degree, to an open position in which the inlet openings of the inner tube and the outer tube come to overlap and beer from the interior of the party keg starts to enter initially the hollow space in the inner tube and then to leave the keg through the outlet opening.
In addition, this publication further discloses a tap which is opened by rotating the inner tube relative to the outer tube in order to trigger the tapping process. To this end, there is provided a guiding groove which extends spirally about the inner tube and which is engaged by a guide pin firmly connected to the outer tube in the area of the wall of the fluid container. Thus, when the inner tube is rotated in the suitable sense, the inner tube moves axially in outward direction until finally, in an end position, the inlet openings of the inner tube and the outer tube come to overlap each other so as to permit fluid to leave the container.
However, such an arrangement is very cumbersome from a handling point of view and leads in addition to considerable problems in terms of sealing.
It generally has to be considered in connection with such taps, if they are to be suited for tapping fluid from containers in which an overpressure prevails, such as a party keg, that considerable problems arise in connection with the safe sealing under all operating conditions, because it has to be taken into account that an inner pressure of approximately 1 to 1.5 bars prevails for example inside a beer keg, even in cooled and undisturbed condition, and that higher pressures of some bars may be reached for beer which is not sufficiently cooled or that has been shaken inadvertently.
Although it is generally possible to achieve proper sealing by different, sufficiently sized sealing surfaces, the contact pressures required between the different sealing surfaces generally have the result that moving the tap will in part be possible only by application of considerable forces in order to overcome the friction caused by the high contact pressure.